Electric switch



Nov. s, 1928. 1,690,103 E. L. CLARK ELECTRIC SWITCH Filed June 5, 1924 2 Sheets-Sheet 1 0 I INVENTOR WITNESSES:

TTCRNEY E. L. CLARK ELECTRIC SWITCH Nov. 6, 1928.

2 Sheets-Sheet 2 Filed June '5, 1924 6 V K w map m m W4 9. 0 0 mm M w L MB F y z .2 1 fifiht f M. M w w w W MW 3 3 MW 9 9 R g H M a ,QPDIIMHHHH 5 wh 3 E g m a m R M A TORNEY Patented Nov. 6, 1928.

UNITED STATES 1,690,103 PATENT OFFICE.

EMERSON L. CLARK, 0F PITTSBURGH, PENNSYLVANIA, ,ASSIGNOR TO SYNTRON COM- IPANY, A CORPORATION OF DELAWARE.

ELECTRIC SWITCH.

. Application filed June a, 1924. Serial No. 717,468.

My invention relates to electric switches of the snap action type and particularly adapted for use as trigger switches for electric tools.

One object of my invention is to provide a trigger switch for controlling the operation of a portable electric tool, that shall close with a snap action when operated and that shall open with a snap action when released.

Another object of my invention is to provide a snap switch comprising a bridging element arranged to present different engaging surfaces to stationary contact members during consecutive operations;

Another object of my invention is to pro vide a snap switch of the above character thatshall be simple and rugged in construction,

comprising a single supporting elementupon which shall be mounted the operating mechanism and the cooperating contact members and that shall further embody means for controlling the extent of movement of the operating mechanism.

The switch embodying my invention is constructed and arranged to permit its insertion in the handle of the portable electric tool. The switch comprises a supporting element upon which two stationary .contact members are mounted and a toggle mechanism opera-.

tive by a trigger handle or lever to effect enga genicnt or disengagement of the stationary contact members and a movable contact member. The movable contact member isdisposed to revolve about its axis after each disengagement to present difi'erent engaging surfaces to the stationary contact members at the nextoperation. By means of such construction, the wear is more evenly distributed over the surface of the bridging contact member and the disadvantages of continuous arcing at the same points are obviated. An over center spring operates to break the toggle in both directions to efi'ect a snap action movement of the bridging contact member controlled by the toggle. When the trigger handie or lever is released, a retrieving spring controls the toggle to open the switch.

The construction of the switch is illus trated in the accompanying drawings in which-- Fig. 1 illustrates the disposition of the switch in the handle of a portable electric tool;

Fig. 2 is a plan view of the switch structure with the seating cap removed;

Fig. 3 is a side view of the switch; i

Fig. 4 is abottom view of the switch illustrated in Figs. 2 and 3;

Figs. 5, 6 and 7 are end sectional, and plan and side elevational views, respectively, of the seating cap upon which. the switch is supported when disposed in the handle of the electric tool;

Figs. 8 and 9 are end and plan views of the bridging contact support which also serves as the free link of the toggle mechanism of the switch;

Fig. 10 is a plan view of the same support and free link illustrating its original outline;

Fig. 11-is a plan view of the main supporting member as originally stamped from a sheet of metal;

Figs. 12-, 1.3 and 14 are side, front and bottom elevational views, respectively, of the main supporting member in its "nal form;

Fig. 15 is a downward view 0 the supporting member illustrated in Fig. 1?), taken along the line XVXV.

Figs. 16 and 17 are Ian and end views, respeotlvely, of the free ink illustrated in Figs. 8, 9 and 10, showing the disposition and construction of the rotatable bridging contact member;

Figs. 18 and 19 are side and front views illustrating the disposition of the retrieving spring on the main support member;

Figs. 20, 21 and 22 are side, front and plan views respectively of the trigger handle lever for the switch;

Fig. 23is a sectional view of the cylinder bushingfor supporting the bridging contact member of the free link illustrated in Fig. 16;

Fig. 24 is a plan view of a lock washer for fecluring the bushing of Fig. 23 to the free in r;

Fig. 25 is a front view of the spring clip used to secure the spring to the toggle pin;

Fig. 26 is a front view of an anchor for anchoring the retrieving spring at the base of trated in Fig. 27, showing the threaded sockets disposed therein;

Fig. 30 is a sectional view of one of the sockets, illustrating its internal threaded construction;

Figs. 31 and 32 are plan and side views of a threaded socket illustrated in Fig. 30;

Figs. 33 and 34 are front and side views respectively, in elevation, of the spring strips that constitute the stationary contact members;

Figs. 35 and 36 are plan and edge views respectively, of insulating paper disposed between the spring contact strips illustrated in Figs. 33 and 34, and the insulating supporting block therefor illustrated in Fig. 27;

Figs. 37 and 38. are plan and end views respectively, in elevation, of a fibre cover disposed around the supporting block and the stationary contact members disposed thereon;

Fig. 39 is a plan view of a strip of flexible material such as a thin sheet of soft steel, serving to lock the fibre cover in position around the stationary contact member; and

Figs. 40 and 41 are back and side views respectively, in elevation, of the dust guard disposed on the switch to close the opening in the handle through which the trigger hanle or lever extends.

As illustrated in Figs. 1 and 3, the switch is supported from a. recessed cover or seating cap 50 by means of which the switch may be inserted into or removed from the handle of the tool as a unit.

The switch is secured to and supported from the under side of the cover 50 and comprises, in general, a main supporting element 51, a pair of stationary contact members 52, supported thereon, a movable contact member 53 for bridging the stationary contact members, a toggle mechanism 54 operated by a trigger handle or lever 55 for operating the switch, over-center springs 56 for effecting the operation of the switch with a snap action, and a retrieving spring 57 for opening the switch when the trigger lever 55 is released.

The main supporting member 51 constitutes a stamping of sheet metal and is provided with two flange or wing portions 58 and 59 that are respectively provided with an anchoring tip 60 which extends through the cover 50 and is then beaded down to anchor the wing portion in position. These anchor wing portions 58 and 59 serve to strengthen and assist the supporting member 51 to resist turning moments developed in operation of the switch, and they also serve to support the main fulcrum pivot for the operating trigger lever 55. The supporting member 51 is also secured to the cover 50 by a rivet 61.

The supporting member 51 is provided with a portion 62 that serves as a stop surface for the contact supporting or free link of the toggle. Two stops, 63 and 64, are disposed on the sides of the main supporting member 51 and serve to limit the extent of movement of the operating lever and the toggle mechanism by the retrieving spring 57.

The supporting member 51 is further provided with a contact supporting portion 65 that is provided with four fingers 66 that grasp and support an insulating block 67 upon which stationary contact members 5:! are mounted. The block is provided with rccesses into which the fingers fit. A tip (58 is also disposed on the contact supporting portion (35 and it is engaged by a locking arm (39 provided with an opening 70 to receive the tip 68 and which locks the support portion (35 in position to preclude displacement thereof by the turning moments developed by the actuation of the switch. The top surface 71 of the supporting portion 65 serves as a stop for the con act supporting link of the toggle mechanism, and limits the extent of its move ment by the over-center springs 56.

The operating mechanism of the switch comprises the operating lever and the toggle controlled thereby to actuate the movable contact member 53. The operating lever 55 constitutes a channel-shape bifurcated member provided with two extending portions 7'). and 73 that will be referred to as operating link elements. The operating lever is also provided with two spring anchoring elements 74 and 75. The operating link elements 72 and 73 fit over the wing portions 58 and 59 of the supporting member 51 and are supported and pivoted on a pin 76 extending through and supported by the wing portions 58 and 59. The pin 76 serves as a fulcrum for the operating lever 55 and its associated operating link elements 72 and 73. The links 79. and 73 also support a pin 77 between their respective ends upon which is pivoted a free link 78 illustrated in Figs. 8. 9, 10, 16 and 17.

The free link 78 comprises two recessed pivot surfaces 79, that engage the pin 77, two laterally extending arms 81 and 82. and a contact supporting arm 83. Two springs 56 are disposed between the arms 81 and 82 of the free link 78 and the anchoring elements 74 and 75, respectively, of the operating lever 55. Since the free link is a flat stamping. a bushing 84: is disposed on the contact supporting arm 83 to present a cylindrical sur face of rotation for the rotating contact member 53. The contact member 53 is supported on a ring 85 of insulating material which is adapted to rotate on the bushing 84-. A lock washer 86 fits over the end of the arm 82} and the latter is headed to hold the bushing and the contact member in position.

The operating link elements 72 and 73 and the free link 78 constitute the toggle mechanism for actuating the movable contact member 53. By means of the over-center springs 56, the contact member 53 is open ated with a snap action. Since the anchoring elements 74 and for the over center'springs 56 shift about the fulcrum pin 7 6 when the operating lever 55 is operated, the springs are more rapidly shifted with respect to the center pin of the toggle and the snap action operation of the contact member is more rapidly and positively effected. By means of the construction employed, the anchor points of sequently, a quicker operation of the switch.

The movement of the free link 7 8 which carries the bridging contact member 53, is limited by the stop surfaces 62 and 71 of the ma n supporting member 51. The stationary spring contact members 52 are so disposed as to be engaged and bridged ,b the contact member 53 when it is actuate to its power position at which the free link engages the lower stop 71.

'In an electric tool such as an electric drill or an electric hammer, to which the present switch is articularly adaptable, it is desirable that tlie switchbe opened when the operative lever is released. To accomplish this,

the retrieving spring 57 is disposed between an anchor 87 in the lowersection ofthe sup port member 51 and a spring clip 88 supported on the center pin 7 7 of the toggle. When the switch is operated to closed position, the retrieving spring 57 is tensioned, and, consequently, when the operating lever 55 is released the spring 57 straightens the toggle and then breaks it again to disenga e the bridge contact member 53 from the stationary contact members 52. When the switch is actuated toits closed position, the movement of the bridging contact member 53 is such, by reason of the path of the center pin of the toggle, that a combined vertical downward and horizontal wiping action is effected between the bridging contact member and the stationary contact members. The disadvantages of loose or hi h resistance contacts, due to dust, etc., are t usobviated. When the switchis opened, the movable contact member 53, by reason of its mass and the snap action of the tog le, will turn or rotate on the bushing 84. ,wo different surfaces will consequently, be presented for engagement with the stationary contact members, when the switch is again operated. By such construction, the wear and pitting, due to arcing, of the? movable contact member will be evenly distributed. There is thus no change for loose engagement or sticking between the contact surfaces of the movable and the stationary contact members.

The stationary contact members are supported on the insulating block 67 by small screws 89 threaded into threaded sockets 91 which are molded in the block 67. A layer of insulating fish paper 92 is disposed between the stationary contact members 52 and the block 67 to insulate the contact members from engageable operating arm angularl the fingers 66 that support the contact block 67 Terminal clips or other conductors may then be secured to the contact members 52 by the lower set of the screws 89. A fibre cover 93 is then disposed around the contact mem- .bers andthe supporting block therefor, and it is held in position by a small strip 94 ot' flexible material such as soft steel, which extends through two openings 95 in the fibre cover and a recess 96in the side of the contact block adjacentthe block supporting portion 65. The ends of the strip 94 are bent over to lock the fibre'cover in position and the switch is then ready for insertion in the handle of the tool.

Since the handle of the electric tool must be provided with an opening to permit the trigger or operating lever of the switch to extend through, it is desirable to provide a closure therefor after the switch is in position. For

this purpose I provide a dust guard 97 comprising a member of L-shape, one side of which is secured to the main support member 51 and the other side of which covers the opening through which the operating lever extends.

By means of the construction which I have herein illustrated, a snap action of the switch is effected both to opening and to closing position, and the movable contact memher is caused to present different surfaces of engagement for consecutive operations.

My invention is not limited to the specific structural details that are illustrated since they may be modified Without departing from the spirit and scope .of the invention, as set forth in the appended claims.

I claim as my invention:

l. A snap switch adapted to be enclosed in the hollow handle of a portable tool, comprising a pivoted toggle link having a manually related with respect to said handle, a free lin pivoted at or adjacent he end of said toggle link, a movable contact member carried by said free link, stationary contact members adapted to be bridged by said contact member, over-center spring mechanism connected to said links for moving said movable contact member into engagement with said stationary contact mem ers upon actuation of said operating arm, and means tor'biasing said movable contact member from said stationary contact Hill members and for moving said operating arm 3. A snap switch adapted to be enclosed in the hollow handle of a portable tool, comprising an angular supporting frame carried by said handle, an operating member pivoted to an extension of said frame and having a toggle link extending in one direction and an arm extending in substantially the opposite direction, a free link pivoted at or adjacent the end of said toggle link, a movable contact member carried by said free link, stationary contact members carried by another extension of said frame for co-action with said movable contact member, and over-center spring mechanism connected to said free link and to the arm of said operating member.

at. A snap switch comprising a supporting member of substantially C-shape having its end surfaces adjacently disposed and provided with two backwardly extending wing portions, disposed substantially opposite the opening or space between the end surfaces, a pin supported by the wing portions, a link pivoted on the pin as a fulcrum, and provided with an operating lever, a second link pivoted on the free end of the first link and movable in the space between the end surfaces of the supporting member, and an over-center spring for effecting snap action of the second link in either direction when the first link is moved past the dead-center position.

5. A snap switch comprising a supporting member of substantially C-shape having its ends surfaces disposed longitudinally adjacent each other in spaced relation, a bracket disposed substantially opposite the space between the ends of the supporting member, a link pivoted on the bracket and provided with a free end extending within the zone of the supporting member adjacent the space between the ends thereof, a pin supported by the free end, a free link pivoted on said pin and movable between the spaced ends of the supporting member, a switch member disposed on and controlled by the free link, an overcenter spring between the links to actuate the free link with a snap action between the spaced ends of the supporting member as stops, an operating lever for the pivoted link for effecting actuation of the switch member to closing position, and a retrieving spring anchored within the supporting member to the base thereof and secured to the pivot of the free end of the pivoted link to actuate the switch member to open position when the opcrating lever is released.

0. A snap switch comprising a supporting member of substantially C-shape whose ends are adjaeently spaced to serve as stop surfaces. a stationary pin disposed beyond the wall of the supporting member opposite the stop surfaces, an operating link pivoted thereon and extending within the enclosure of the supporting member and movable therein adjacent the stop surfaces, a free link pivoted on the movable end of the operating link and extending through the space between the stop surfaces, a switch device controlled by the free link to open or close an electric circuit, an over-center spring between the links to actuate the switch device with a snap action, an operating lever for actuating the operating link to close the circuit, and a retrieving spring for actuating the link to open the circuit.

7. A snap switch comprising a supporting member of substantially C-shape constituting a bracing wall, a supporting wall and a head-stop, stationary contact members disposed on the support-ing wall, a movable contact member for bridging said stationary members, toggle mechanism comprising an operating link and a free link for controlling the movable contact member, said free link being movable between the head-stop and the end surface of the supporting wall serving as a stop, means for pivotally supporting the operating link on the bracing wall, and means for locking the supporting wall to the bracing wall to preclude displacement of the supporting wall by displacing torques established by actuation of the movable member to engagement with the stationary contact members disposed on the supporting member.

8. In a snap switch, the combination with stationary and movable contact members and operating means for effecting engagement and disengagement thereof, of means for supporting the contact members and operating means comprising an integral member provided with a bracing element for supporting the ope ating means and limiting the extent of its movement, a supporting element for supporting the stationary contact members, a. locking element for maintaining the supporting element in position against the displacing torques established by the engagement of the movable and the stationary contact members, and a stop element cooperating 'ith an end surface of the supporting element to limit the extent of movement of the movable contact member.

9. A snap switch comprising a support member of substantially rectangular shape having an open space in one side wall near its top, a toggle mechanism provided with an operating member pivoted outside of the rectangle but ha\ing its free end extending thereinto, with a free link pivoted to the free end of the operating link within the rectangle area and extending outward through the spare in the side wall, the surfaces of the wall including the open space serving as stops for the free link, an operating spring between the links ror cilia-ting snap il('1 ion of the free link to actuate a contact member, an operating lever on the operating link, and a retrieving spring anchored within the rectangle to the base thereof and secured to the pivot point joining the two links for returnlit ing the links to their initial positions when the operating lever is released.

10. A snap switch com rising a seating member, a supporting mem er secured thereto and provided with anchoring elements to sustain the supporting member against tension and compression stresses, a toggle mechanism supported on the supporting member and provided with an-operating link and a free link, means serving as stop elements for the free link, contact members supported on and insulated from the supporting member, a contact controlled b the :free link to engage said contact mem rs upon actuation of the operating link, and a restraining spring for effecting disengagement of the contact members when the operating link is released.

11. A snap switch comprising a. seat member, a support member perpendicularly secured thereto and provided with later ally disposed wing portions anchored to the seat member to sustain the support element against displacing forces, a'toggle mechanism comprising a bifurcated member of substantially channel shape embodying two elements pivotally mounted on the wing p or-, tions of the support member and extendlng beyond the support member, and a freelin'k pivotally mounted between said two elements of the bifurcated member and embodying two laterally extending arms, a spring disposed between each armof the free link and the corresponding element of the bifurcated member to constitute an over-center spring for effecting snap action of the free link a switch element controlled b the free link or effecting e agement or isengagement of I contact mem ers, anda retrieving spring for controlling the tog le mechanism. I

12. A snap switc comprising'a seat member, a support secured thereto provided with perpendicularly extending 'wing portions anchored to sustain the support member, toging spring for controlling the to gle mechs 5.5,

anism, and means integral with t e support member serving as stops for the respective links. a v

- In testimony whereof, I have hereunto subscribed my name this 17th day of May, 1924.

' EMERSON L CLARK. 

